Ion transport membranes (ITMs) consist of ionic and mixed-conducting ceramic oxides that conduct oxygen ions at elevated temperatures of 1475-1650 F. Air is compressed to about 230 psia, heated to 1650 F, and fed to ITM. Hot oxygen permeates through the membranes. The permeate pressure has to be kept low to provide oxygen partial pressure driving force across the membrane. Typically, 50% to 80% oxygen recovery seems possible.